Illiyin is a term mentioned in the Quran (Surah Al-Mutaffifin) referring to a "register" or a "place" where the records of the righteous are kept. It is described as being in the highest reaches of the heavens. The term implies a state of high honor and divine proximity. While the "Sijjin" is the register of the wicked in the depths, Illiyin represents the ultimate preservation of every good deed and the exalted station of those who lived a life of "Taqwa." It serves as a powerful motivator for believers to strive for excellence in their conduct.